Rewrite a critical Node.js service in Go overnight

Checkly built ~600 black-box tests from production scenarios first; Claude Code wrote 13k lines of Go and servers went 20→5.

In short

What it does: Checkly built ~600 black-box tests from production scenarios first; Claude Code wrote 13k lines of Go and servers went 20→5.

Agent: Claude · Category: Coding

Steps in brief:

  1. Build black-box tests from real production scenarios (Checkly had about 600).
  2. Have Claude Code rewrite the service in the target language.
  3. Run the same tests against the new service before switching traffic.

Who made it: Checkly (X post, 29 Sep 2026) · source

Last updated · based on 336 use cases on agentsetups, each credited to its author.

by Checkly29 Sep 2026

Prompt for your agent

Goal: Port a service to a new language with black-box tests as the safety net.
Setup: agents used in source: Claude.
Steps:
1. Build black-box tests from real production scenarios (Checkly had about 600).
2. Have Claude Code rewrite the service in the target language.
3. Run the same tests against the new service before switching traffic.
Rules: ask me before anything irreversible (sending, posting, paying, deleting); don’t invent data, results or tools I haven’t given you; tell me what you couldn’t verify.
Based on: Checkly — https://x.com/checklyHQ/status/2104919645790544282 (summarised from source; the source has no explicit step list)

Steps are our summary of the source (it has no explicit step list). Includes a “Based on” credit line.

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